TITLE:   GCN CIRCULAR
NUMBER:  14438
SUBJECT: GRB 130418A: Continued RATIR Optical and NIR Observations
DATE:    13/04/22 21:17:15 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM),
Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130418A (de Pasquale et al., GCN 14377) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional
on Sierra San Pedro Mártir from 2013/04 22.14 to 2013/04 22.33 UTC (80.35
to 84.95 hours after the BAT trigger), obtaining a total of 2.84 hours
exposure in the r' and i' bands and 1.19 hours exposure in the Z, Y, J, and
H bands.


At the position of the transient observed on 2013/04/19 (GCN 14388) and
2013/04/20 (GCN 14404), in comparison with SDSS DR8 and 2MASS, we obtain
the following upper limits (3-sigma) in the AB magnitude system:

 r'> 23.12
 i'> 22.93
 Z > 22.52
 Y > 21.89
 J > 21.85
 H > 21.25

These magnitudes are not corrected for Galactic extinction in the direction
of the GRB.  The source is thus more than about 1 magnitude fainter than it
was observed to be two days ago.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.